USB Isolation Circuit for Medical Device Leakage Current Protection
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Solution Overview
Problem
Medical devices are vulnerable to increased leakage current risks when connected to self-powered USB peripheral devices that draw power from external sources, potentially compromising patient safety by creating a path for leakage current.
Innovation Solution
A method is implemented to determine if a USB peripheral device is connected to a medical device and if it is drawing power from an external source, providing an indication of a potentially unsafe condition and electrically isolating the device to prevent leakage current, using a current detection circuit and processing devices to monitor USB data lines and power supply lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a USB peripheral device is connected to a medical device, then the medical device can provide data communication or additional functionality, but the leakage current safety standards may be compromised due to external power sources
Solution Approach 1:
The patent introduces a USB isolation device as an intermediary component between the USB peripheral device and the medical device. This isolation device includes a USB host controller that electrically isolates the medical device from the externally powered USB peripheral device, allowing data communication while blocking harmful leakage currents. The isolation device acts as a mediator that enables connectivity functionality while preventing the harmful electrical interaction that would compromise safety standards.
2Reliability
If the medical device monitors current draw to detect self-powered devices, then patient safety can be enhanced, but the device complexity increases due to additional monitoring circuits
Solution Approach 1:
The patent implements preliminary action by having the medical device's USB host controller proactively monitor the current draw on the VBUS line before connecting to or during connection with a USB peripheral device. By detecting whether the peripheral device is drawing significant current (indicating it is self-powered) in advance, the system can prevent unsafe connections from being established. This preliminary detection approach enhances patient safety by identifying potential hazards before they can cause harm, while the monitoring is integrated into the existing USB host controller functionality.
Data Source
AI summary
This patent application relates generally to identifying a self-powered device connected to a medical device.